1. Field of the Invention
The invention relates generally to a centrifugal pumping apparatus of the type wherein a hollow casing is supplied with fluid to be pumped and the casing rotates about a stationary pitot tube having its opening opposed to the direction of rotation of the fluid in the rotating casing.
2. Description of the Prior Art
U.S. Pat. No. 3,838,939 discloses the basic structural details and operation characteristics of a typical pitot centrifugal pump. The pump includes a rotating casing and a stationary pitot or pick-up tube within the casing. The fluid to be pumped enters an intake manifold and passes into a rotating casing wherein the fluid is accelerated to the rotational velocity of the casing. A pitot tube has an opening facing the direction of rotation of the rotating fluid and hence a jet-like stream of fluid is forced into the pitot tube and flows from the pitot tube to an outlet through an axial passage defined by a hollow shaft on which the pitot tube is mounted. Fairly complex and expensive bearings are provided for mounting the casing for rotation relative to the pick-up tube and, at a still further manufacturing cost penalty, complicated sealing arrangements are provided to prevent any of the fluid being pumped from contacting the bearings, and a separate lubrication system is required. This relatively complicated and costly design is believed to be necessary because the bearing materials heretofore employed were relatively soft and hence subject to rapid abrasive wear if the fluid being pumped contained any significant amounts of particulates. In oil field pumping applications, it is well known that substantially all of the fluid required to be pumped contains significant amounts of sand, and therefore a significant manufacturing cost penalty was incurred to provide elaborate sealing and lubricating arrangements for insuring that the bearings would not be contacted by the particulate-containing fluid being pumped.